MEIKO and the other VIRTUAL SINGERS live in a world called SEKAI, but appear in the real world to consult people who have trouble understanding their true feelings through music. She does not have any intention of helping the group, but only observes them from a distance. According to her, people should be able to overcome their problems with their own strengths. MEIKO appears as part of the SEKAI during the Secret Distance event story.
(Quoted from Project Sekai's Fandom page - https://projectsekai.fandom.com/wiki/MEIKO)

We're looking for a well-balanced singer with a warm, feminine voice.
Please send me two clips: one of your normal, speaking voice using the lines provided and more if you want, and one of your singing - of any song MEIKO is in.
Vocal Reference: https://www.youtube.com/watch?v=HHZqQFqC74Y
Voice Reference: https://www.youtube.com/watch?v=K3kchJtVSgw&list=PLk-RPbe5veVYpUUuQlfH45uwqSUnsu9iq&index=2